using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace NGS
{
    class Program
    {
        static void Main(string[] args)
        {
            var inputs = Console.ReadLine().Split(' ');

            var a1 = Int32.Parse(inputs[0]);
            var a2 = Int32.Parse(inputs[1]);
            var a3 = Int32.Parse(inputs[2]);

            var r = (a2 - a3) / (a1 - a2);
            var d = a2 - (r * a1);

            var result = (a3 * r) + d;

            Console.Write(result + "\n");
        }
    }
}